Fine electric guitars made of wood and wood composites that have excellent acoustic qualities have been made for over half a century. Guitars of this type tend to be made by artisans who have assimilated the knowledge accumulated over the years by trial and error. Frequently exotic woods are used to achieve high fidelity. In order to compensate for warping and dimensional changes due to alterations in temperature and humidity, laminates are used in an attempt to correct for these effects. The lack of stiffness and strength of wood under constant tension from the strings and exposed to other forms of mechanical stress and impacts has been a problem, partially addressed by the use of metal truss rods. Mechanical accuracy is difficult to achieve and maintain. Wood instruments require continuous retuning to compensate for these effects. No two guitars will have exactly the same sound and tuning properties using this approach.
Improvements suggesting the use of metals, most prominently aluminum and composites made of carbon fiber and plastics have developed over the years to address the deficiencies in the structural properties of wood and attempt to alter and improve the acoustic properties. An improvement in the resistance to dimensional changes in response to humidity was achieved using these new materials. The use of aluminum to control thermal expansion and contraction is problematic as the thermal conductivity is high causing it to expand and contract quickly in response to changes in temperature and alter the tune. This is exacerbated by using different metals for the acoustic elements such as stainless steel strings that have a much slower response to temperature changes than aluminum and large differences in their thermal expansion coefficients. Aluminum and graphite based neck structures do not closely match the strings with respect to either their resonate properties or their in their response to temperature changes.
The light weight of aluminum and graphite and the ability to either extrude or mold complex shapes led to many different variations on the theme of a guitar neck. Various types of open channels in the neck were designed to lower the weight and to provide conduits to transfer the vibrations of the strings to the electronic pick-ups. Convex and concave channels were added in an attempt to improve the grip of the hand (U.S. Pat. No. 5,337,643). Frets and fret boards were attached to the neck by bonding, bolting, welding, or press fitting different materials (U.S. Pat. No. 4,189,974), in some instances creating a different material on the aluminum surface by introducing oxide surfaces with an anodizing process (US 201020266734 A1). Enclosing the channels with the fret boards of different materials from the neck to create channel shaped tubular structures (U.S. Pat. No. 3,915,049; U.S. Pat. No. 4,145,948; U.S. Pat. No. 4,359,924) were also described. Other times the channels and grooves were left open to the air (U.S. Pat. Nos. 3,915,049; 4,189,974; 5,337,643; US APP 20120266734). The creation of a channel shape gave the neck the mechanical characteristics of a beam which was noted to add to the inherent strength of the structure allowing the use of thinner walls, lighter weight, and eliminate the truss rod.
As is the case with the development of any devises over periods of time and much iteration, some historical design characteristics can persist, for better or worse. Examples abound in all fields from tools (slotted screw drivers) to transportation (spacing of railroad rails dates back to ruts created by Roman chariots in the major roads of Europe), to communications and computers (Ctrl-Alt-Delete). The flat or slightly curved surface of the finger and fret board of a guitar is an example of a fundamental design principle that has been passed down through the ages and appears on all guitars made today.
The shape of the fret and fret boards of these aluminum and graphite based necks has remained substantially unchanged from their wooden counterparts as did the material of the strings, primarily steel or brass wrapped steel. Fret boards continued to have a long radius of curvature, typically greater than 10 inches, or remained flat resulting in a radius of curvature of infinite dimensions. The geometries of the front of the neck, where the strings lie, and the back of the neck, where the palm of the hand rests, remain substantially dissimilar for reasons that are not immediately obvious other than historical precedence and general familiarity with a particular feel that develops with a musician with many hours of practice. We propose a different design that has better ergonomic properties and a substantially different feel than current state of the art.
In order to maintain the different geometry of the front and back of the neck and its associated functional elements, the frets and fret boards have been generally constructed from multiple parts, frequently of dissimilar materials having different acoustic properties. This requires the use of glues and fasteners of various ilk's which should not be viewed as advantageous as they can only inhibit the transfer of vibrations with high fidelity resulting in sound deadening effects. In addition this complicates manufacture and compromises the achieving of precision and accuracy on a routine basis. Thus the historical geometry has led to manufacturing constraints that limit the ability to achieve high acoustic fidelity in a simple and reproducible manner.
In one instance a neck of aluminum was described with the frets and fret board machined into an flat surface on the neck to achieve a one piece neck and fret board design to eliminate some of these issues. Open longitudinal channels on the back of the neck were required to reduce the weight and improve sound transfer to the pickups. However, as with other designs, the geometrical shape of the fret board and the back of the neck did not change. The curvature of the front and back were substantially different (US application 2012/0266734 A1). Anodizing was required to provide sufficient surface hardness to avoid the stainless steel strings from wearing out the frets. The anodized surface itself constitutes a material discontinuity within the neck that can distort the resonate properties and result in a sound deadening effect thus negating many of the gains of machining from a single piece of metal.
The magnetic pickups are generally mounted outside the neck, on the body, or are embedded in an open cavity in the body or neck of the guitar to provide additional shielding to reduce unwanted electronic and acoustical noise. Hollow cavities inside the neck have not been exploited for pick-up mounting and shielding. U.S. Pat. No. 4,145,948 describes a carbon fiber neck with a u-shaped channel covered with a fret board and suggests that electronics could be put in the channel but does not describe or show how this is done.
We herein describe a new design for the neck of an electrical stringed instrument best embodied in an electric guitar of all types but also applicable to other stringed musical instruments. The neck is made from a single tube of a non-magnetic steel alloy, preferably stainless steel, with the frets machined into the surface of the tube. The acoustic properties and the ability to achieve and maintain proper tune over time in the presence of environmental extremes of temperature and humidity is superior to previous approaches. The shape of the neck is a radical departure from the prior art and provides ergonomic advantages more suitable to the natural grip of the human hand. This design allows for scalable manufacturing with a high degree of precision and accuracy. It also provides an ideal cavity within the tube to insert electronic magnetic pick-ups of a new design that are naturally shielded from external electrical and acoustic noise. The design is inherently stronger than other approaches resulting in an instrument resistant to mechanical damage even under situations of extreme impact.